Short run pipe heating solution

[LigouriRd]

I have one bathroom where the copper toilet supply runs through the slab near the exterior of the house that occasionally freezes when we get sub zero temperatures. What can I do to safely and permanently prevent this?
I have looked into some of the heating cables (EasyHeat, Frost King) but they warn not to install on a pipe shorter than 3' or to spiral the installation. I doubt that, even if I open up the drywall, I will have much more than a few feet until I hit the slab.

PS: I have temporarily unfroze the line by aiming a small space heater at the line. I really don't feel like this is safe in the long run.

 

[jack stand]

Do you feel that the freezing occurs in the slab, or in the wall?
The wall will be much easier to attempt a cure by filling around the pipe on 3 sides. (outside, above and below leaving any inside heat available on the pipe)
The slab is more likely the problem, and not nearly as simple to correct.

 

[mike93lx]

Can't run a new line?

 

[Two Door]

Some of the short cables show, at least in the advertising, that they can be wrapped. I have a similar situation and just ordered the Wrap-On brand. Of course, with a small diameter pipe, even that may not help enough.

 

[LigouriRd]

My guess is that the freezing is in the slab, the line is about a foot from the exterior wall and has fiberglass insulation around it.

It would be pretty difficult to run new line though finished rooms, that would be the alternative if nothing else works.

The Wrap-on 31003 is a step in the right direction...it may be challenging to spiral 3' with less than 3" spacing.
I found this: BriskHeat HSTAT051002 but the reviews on it make it seem pretty dangerous.

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[mike93lx]

I'd deal with even some exposed, painted piping before relying on heat tape in the long run. A water leak from a tape failure wouldn't be fun

 

[LigouriRd]

Just cringing at the logistics of getting a contractor to run a new line...this would certainly not be solved before spring arrives. I am very surprised this has not been an issue for the previous two owners of the house since it was built in 1985.

 

[TurnipTruck]

What does the exterior of the slab in that area look like? Can insulation be added underground there?

 

[wssix99]

How old is this house? A supply line going into the slab isn't remotely up to code for our area. I would expect that you would have constant problems. If you are only having problems right now during this cold snap, the issue may be in you walls...

The ground under the slab freezes before the concrete does. (It holds on to heat escaping from the house.)

I would frost protect the foundation with insulation. This will keep the ground under the house from freezing and should also help a little with your heating bills.

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://www.huduser.gov/publications/pdf/fpsfguide.pdf&ved=2ahUKEwjP_cfe5-KDAxX-kmoFHdl3CmUQFnoECBcQAQ&usg=AOvVaw3xleztWxHUqbYOSc8JMB5T

 

[Renegade1LI]

I'm with Mike93lx, run a new line, using pex may make it a little easier. Anytime you can avoid heat trace I would go that option.

 

[NUTTSGT]

I'd probably try to insulate the slab around the outside with some rigid foam.

Probably not going to happen when the ground is frozen.